| From: Miaohe Lin <linmiaohe@huawei.com> |
| Subject: mm/mremap: avoid unneeded do_munmap call |
| |
| When old_len == new_len, do_munmap will return -EINVAL due to len == 0. |
| This errno will be simply ignored because of old_len != new_len check. So |
| it is unnecessary to call do_munmap when old_len == new_len because |
| nothing is actually done. |
| |
| Link: https://lkml.kernel.org/r/20220401081023.37080-1-linmiaohe@huawei.com |
| Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> |
| Acked-by: David Hildenbrand <david@redhat.com> |
| Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
| --- |
| |
| mm/mremap.c | 4 ++-- |
| 1 file changed, 2 insertions(+), 2 deletions(-) |
| |
| --- a/mm/mremap.c~mm-mremap-avoid-unneeded-do_munmap-call |
| +++ a/mm/mremap.c |
| @@ -820,9 +820,9 @@ static unsigned long mremap_to(unsigned |
| goto out; |
| } |
| |
| - if (old_len >= new_len) { |
| + if (old_len > new_len) { |
| ret = do_munmap(mm, addr+new_len, old_len - new_len, uf_unmap); |
| - if (ret && old_len != new_len) |
| + if (ret) |
| goto out; |
| old_len = new_len; |
| } |
| _ |
